Plant Biology Assessment PDF

Plant biology Assessment 1st lecture 1. Plant importance. - Without plants, life on earth would not exist - Primary source of food for people and for animals - Produce oxygen - Help to keep us cool - Renew the air - Slow wind speed - Provide a home for wildl...

Plant biology Assessment 1st lecture 1. Plant importance. - Without plants, life on earth would not exist - Primary source of food for people and for animals - Produce oxygen - Help to keep us cool - Renew the air - Slow wind speed - Provide a home for wildlife - Beautify surroundings - Perfume the air - Furnish buildings materials and fuel - Produce wood pulp for paper products - Source for many medicines - Dyes 2. Similarities and differences between plant and animal cells. Features Plants Animals Excretion a. Produce less waste a. Produce more products metabolic waste b. No specialized products. excretory system b. With special excretory organ or system Growth The growth is indefinitely. Can The growth is definite. Growth grow through continues stops at maturity. occurs throughout life. Mainly occur throughout the whole body at the tips of the roots and the shoots Respiration Lower Higher Movement a. The whole body a. Whole body can move usually fixed to the from place to place. ground, only parts of b. Movement is relatively the body can move fast b. Usually movement is result of growth in low speed Response a. No receptors and a. Have receptors and nervous system nervous system b. Less sensitive and b. Respond more quickly  respond more slowly 2d lecture 4. Plant structure and adaptation. Plants needs to take resources from 2 different environments - Soil: Provides water and minerals - Air: Which is the main source CO2 and light that does not penetrate far fínto soil Plants have evolved 2 systems: a subterranean root system and an aerial shoot system of stems and leaves. These systems depend on each other because they lack chloroplasts and living in the dark roots would starve without the sugar and other organic nutrients important for the photosynthetic tissues of the shoot system. The shoot system, and its reproductive tissues, flowers, depend on water and minerals absorbed from the soil by the roots. Leaves: are the main photosynthetic organs of most plants (but green stems are also photosynthetic ) - While leaves vary extensively in form, they generally consist of a flattened blade and a stalk, the petiole which joins the leaf to a stem node. - In the absence of petioles in grasses and many other monocots, the base of the leaf forms a sheath that envelops the stem. Taxonomists: Use leaf shape, spatial arrangement of leaves, and the pattern of veins to help identify and classify plants. - For example, simple leaves have a single undivided blade, while compound leaves have several leaflets attached to the petiole. - A compound leaf has a bud where its petiole attaches to the stem, not the base of the leaflets. Some plants have leaves that have become adapted by evolution for other functions - This includes tendrils to cling to supporting spines of cacti for defense, leaves modified for water storage and brightly colored leaves that attract pollinators. 5. Differences between monocot and dicot plants. Root system Anchor the plant in the soil, absorb minerals and water, and store food. - Monocots, including grasses generally have fibrous root systems, consisting of a mat of thin roots that spread out below the soil surface - This extends the plant’s exposure to soil water and minerals and anchors it tenaciously to the ground - Most monocots have parallel major veins that run the length of the blade, while dicot leaves have a multi branched network of major veins (netted veination). - Many dicots have a taproot system, consisting of a one large vertical root (the taproot) that produces many small lateral, or branch roots. - The taproots not only anchor the plant in the soil, but they often store food that supports flowering and fruit production later. 6. Root system, functions and structure (external). Most absorption of water and minerals in both systems occurs near the root tips where vast numbers of tiny root hairs increase the surface enormously. Some plants have adventitious roots arising above ground from stems or even from leaves - In some plants including corn, these adventitious roots function as props that help support tall stems. 7. Shoot system, functions and modified shoots. Shoot system Shoots consist of stems and leaves - Shoot systems may be vegetative (leaf bearing) or reproductive (flower bearing) - A stem is a system of nides, the points at which leaves are attached, and internodes the stem segments bw nodes. - At the angle formed by each leaf and the stem is an axillary bud with the potential to form a vegetative branch - Growth of a young shoot is usually concentrated at its apex, where there is a terminal bud with developing leaves and a compact series of nodes and internodes. Terminal buds have special tissue: - Apical meristem: Cells that can divide indefinitely and produce all the differentiated tissues, including vegetative and reproductive organs. - The presence of a terminal bud is partly responsible for inhibiting the growth of axillary buds, a phenomenon called apical dominance. - By concentrating resources on growing taller, apical dominance increases the plant’s exposure to light. In the absence of a terminal bud, the axillary buds break dominance and give rise to a vegetative branch complete with its own terminal bud. 8. Tissue systems and cell types in plants. 9. Dermal tissue in plants. 10. Vascular tissue and vascular cells in plants. 3 different tissue systems: Dermal: - The primary dermal tissue, the epidermis, is generally a single layer of tightly packed cells that covers and protects all young parts of the plant. - The epidermis has other specialized characteristics consistent with the function of the organ it covers - For example the roots hairs are extensions of epidermal cells near the tips of the roots - The epidermis of leaves and most stems secretes a waxy coating, the cuticle, that helps the aerial parts of the plant retain water.  - The secondary dermal tissue, periderm is a multi layer that replaces the epidermis during growth in thickness of stems and roots. - Periderm, after accumulation of more layers of cells further forms outer bark on trees. Vascular: - Continues throughout the plant, is involved in the transport of materials bw roots and shoots - Two types of vascular tissue exists: Xylem- Conveys water and dissolved minerals upward from the roots into the shoots Phloem- Transports food made in mature leaves to the roots and to the non photosynthetic part of the short system. In the Phloem, sucrose, other organic compounds and some mineral ions move through tubes formed by chains of cells, sieve- tube members. Both tracheids and vessels have secondary walls interrupted by pits, thinner regions where only primary walls are present. Tracheids are long, thin cells with tapered end - Water moves from cell to cell mainly through pits - Because their secondary walls are hardened with lignin tracheids function in support as well as transport Vessel elements are generally wider, shooter, thinner walled and less tapered than tracheids - Vessel elements are aligned end to end, forming long micropipes, xylem vessels - The ends are perforated enabling water to flow freely. Ground: Is tissue that is neither dermal tissue nor vascular In dicot stems, ground tissue is divided into: Pith- internal to vascular tissue Cortex- external to the vascular tissue The functions of ground tissue include photosynthesis, storage and support. For example the cortex of a dicot stem typically consists of both fleshy storage cells and think-walled support cells. Seminar 3. Plastids among the plant cells. Their classification and functions. Chloroplasts: Double membrane, stroma, thylacoids, granum, stromal thylakoids or lamellae, DNA, chlorophyll, carotenoids (carotenes, xanthophylls), Enzymes, lecithin. Functions of chloroplasts: - Photosynthesis - Synthesis of DNA and RNA amino acids and some proteins - Synthesis of fatty acids, lipids, phytohormones, vitamins and secondary metabolites - Main nutrient value of green grasses and vegetables Chloroplast conversion into chromoplast: Chloroplasts convert into chromoplasts as plants age or fruits ripen, changing from green to red, orange, or yellow. This transformation involves chlorophyll breakdown, structural changes and carotenoid accumulation, resulting in vibrant colors that attract animals for seed dispersal Chromoplasts Are found in fruits, flowers, roots, and stressed aging leaves, and responsible for their distinctive colors. This is always associated with a massive increase in the accumulation of carotenoid pigments. The conversion of chloroplasts to chromoplasts in ripenníng is a classic example 11. Microscope parts and microscoping techniques. Easy 2d practical work (reserved nutrients) 12. Carbohydrates (as a reserved nutrients) in plants/cells. The main carbohydrate that plants produce is starch. Starch is the main form in which plants store carbon Starch occurs as semi crystalline granules, composed of branched and linear polymers of glucose Starch granules vary in size and shape bw plant organs and bw species  The distinctive morphology and anatomy of starch granules enables identification of plants as it remains in food. Simple: When a starch has a nucleus with the form as a circle Compound: When the starch has a line in the middle Concentric: When the formation of the nucleus is located in the middle Eccentric: When the nucleus is located at the side 13. Fats (as a reserved nutrients) in plants/cells. Storage lipids may be accumulated in one or both of the main types of seeds tissue: - Embryo: The major sites of lipid accumulation in oilseeds are the cotyledons of the embryo. - Endosperm: In some species endosperm is the main site of lipid accumulation 14. Proteins (as a reserved nutrients) in plants/cells. Albumins- Soluble in water. Albumins are found mostly in seeds Globulins- Are insoluble in water. They are most frequently found in seeds of leguminous plants Prolanins and Glutelins- Are mostly found in seeds of crop (grains) and form protein called gluten Aleurone layer Aleurone: Another protein found in granules of maturing seeds and tubers. It's the outermost layer of the endosperm, followed by the inner starchy endosperm. The layer of cells is sometimes referred to as the peripheral endosperm.